1. Field of the Invention
The present invention relates to a golf putter which may or may not include an acrylic golf putter head including a solid metal body of predetermined weight and size conforming to U.S. Golf Association (USGA) rules and regulations while still demonstrating a sufficiently high Moment Of Inertia (MOI) to significantly increase the accuracy of the golf putter, when used.
2. Description of the Related Art
Golf clubs are provided in a variety of material, shapes, dimensions, and weights; each head design having a unique function or advantage.
Golf clubs are used in the sport of golf to hit a golf ball. Each club is composed of a shaft with a lance (grip) and a club head. Woods are used for long-distance fairway shots; irons, the most versatile class used for a variety of shots, and putters, used mainly on the green to roll the ball into the cup.
An important variation in different clubs is loft, or the angle between the club's face and the vertical plane. It is loft that makes a golf ball leave the tee on an ascending trajectory, not the angle of swing; virtually all swings contact the ball with a horizontal motion. The impact of the club compresses the ball, while grooves on the clubface give the ball backspin (a clockwise spin when viewed from a parallel standpoint to the left of the ball). Together, the compression and backspin create lift. The majority of woods and irons are labeled with a number; higher numbers indicate shorter shafts and higher lofts, which give the ball a higher and shorter trajectory.
While the variation of clubs can differ greatly between golfers, a set used to play a round of golf must have no more than 14 clubs. A full set typically consists of a driver, two fairway woods (generally 3-woods and 5-woods, a set of irons from 3 to 9, a pitching wedge, a sand wedge, a putter, and one more club of the player's choice. Many players opt to avoid the 3- and 4-irons (which are more difficult to hit). Another common variation is to use only the 3, 5, 7, and 9 out of the numbered irons. The extra space in the player's bag can then be filled with more woods, easier-to-hit “hybrid” clubs, additional high-loft or intermediate wedges, and/or a specialized chipping club or multiple putters.
Putters are a special class of clubs with a loft not exceeding ten degrees and designed primarily to roll the ball along the grass, generally from a point on the putting green towards the cup. Contrary to popular belief, putters do have a loft (often 5 degrees from truly perpendicular at impact) that helps to lift the ball from any indentation it has made. This increases rolling distance and reduces bouncing over the turf.
Each head has one face that contacts the ball during the stroke. Clubs may have two striking faces; as long as they are identical and symmetrical (some putters and chippers are designed in this fashion, and may be used by left or right-handed players). The overwhelming majority of clubs have only one striking face.
An issue identified with golf clubs is a twisting motion of the club head when swinging the golf club. A moment of inertia (MOI) refers to resistance to a twisting of the club face from alignment as the slightly less than two ounce ball is hit by the twelve ounce club head, if and when slightly mis-hit, or when contacted off the sweet spot. This occurs regularly by amateur golfers, especially with longer putts.
Extensive tests show that a ball mis-hit by as little as ¾ of an inch will impart a side spin, which will cause the ball to fall “off target” by as much as approximately eight inches along a twelve (12) foot putt. This same mis-hit could result in as much as a ten to fifteen percent shortfall in distance. With longer putts this can lead to three-putt greens in addition to the missed one-putt holes.
Currently, golf putters come in two shapes and designs. The blade, which is generally an “L” configuration with a sole plate supporting a usually thin standing face. This shape also commonly has one-to-one and a half-ounce heel and toe weights as part of the face and sole casting. Because the putter head weight, for distance “touch” on fast contoured greens is generally between 11 ounces and 12 ounces, the length for most blade putters is 4.0 to 4.5 inches. This limits the moment arm for the heel and toe section to about 1.25 inches long. Since the formula for calculating Moment of Inertia (MOI) is the total head weight (typically express in grams) times the length of the head squared in centimeters between the center of mass and the “sweet spot,” on the face, wherein the MOI is expressed as grams/cm2.
With the blade type design, the MOI of the heel and toe section are computed separately and then added together. The “sweet spot” is the fulcrum point about which the face twists or revolves when mis-hit. Hence, typically MOI of most blade putters is in the range of 3500 to 4000 grams/cm2.
The mallet design is similar, except that the weight is purposely located to the rear of the head, in line with straddling the center of mass and the sweet spot axis. Here, the design rules of the U.S. Golf Association (USGA) come into play in that the head may not be deeper than the head is long, and the face may not be shorter than two-thirds of the head length. Though many mallet designs have a head depth and length of four and five inches, the typical center of mass point has yet to be moved more than 1.6 inches back from the face; even though extremely thin plates or aluminum rings are used to support the “back weighting.” Hence, the typical MOI for the mallet design is 4500 to 5000 grams/cm2. Some manufacturers may advertise a higher MOI, but this is the result of using a heavier than desirable head weight.
Independent tests done by Golf Magazine for three years running using six to eight of the most popular putters, machine struck at a 12-foot flat distance, show the “falling off” line, when 0.75 inches miss-struck, to be from 6 to 10 inches. Similar “distance tests” were performed using the same clubs at a 16-foot distance. Here the “short fall” with a 0.75 inch mis-hit ranged from 10% to 14%. This extrapolates to 3% average (plus) per 0.25 inch and proportional to the MOI, as above. Accordingly, present putters are so similar in MOI that little, in any difference, in strokes saved is likely.
The typical professional golfer uses an average of 30 putts per 18 holes. The typical mid- to high-handicap player uses 38-40 putts per round. Certainly, most of the difference is due to practice, better ability to read the green, plus a more consistent stroke that allows the golfer to consistently strike the ball on the “sweet spot.”
It is estimated that one-half of this 8-10 stroke difference is caused by mis-hitting the ball. Perhaps if a significantly higher MOI club could be developed, where striking the ball on the sweet spot was not so important, part of those 4-5 strokes could be saved.
Thus, what is desired is a means for putting a golf ball in repeatable manner, by providing a golf putter with a substantially higher MOI putter head.